The decision is that of the judge, not the prosecution. The prosecutor may be silent without being thought to approve of the application. It would after all only be under consideration if the prosecutor sought the admission of the evidence.

Not sure I understand your answer. Off course it would be only be under consideration if they wish to admit certain evidence , so if they stay silent and don't contest something that could result in a weaker case , then is that not saying that the PACE 78 should be accepted?

My 2nd question is assuming that PACE 78 is accepted on the basis the arrest was unlawful, does that mean everything during the time in custody is excluded or can the defence introduce as evidence items that it finds supportive. So for example can the defence get the interview tape excluded , custody record , some CCTV footage but introduce a CCTV film that supports its case.

The crime was damaging a code of practice book for £4 , so it is a in custody crime. I might of got this all wrong but I thought a PACE 78 application because of an unlawful arrest , would exclude everything obtained during the unlawful detention. Are you saying that you can apply to get certain things removed , like interview and custody record but keep "the good bits" ie CCTV footage that might support your case

I would imagine that 99.99% of crimes are admitted outside of custody , so the PACE 78 is to exclude searches or interviews so this case is unique from that aspect

The power of the court is to exclude evidence upon which the prosecution wishes to rely. If the defence wishes to rely on similar evidence, s.78 does not provide the court with power to exclude it. Beware however of the requirement of the court to have regard to all the circumstances.

The defence evidence must still reach the basic standards of relevance and quality.

The basis of the question appears still (?) to be the idea that once one bit of the prosecution/investigation goes wrong, what follows is inadmissible. Again, that is a peculiarly US idea. Here the judge assesses each situation and each part of each situation as it arises.